IJSR International Journal of Scientific Research 2277 - 8179 Indian Society for Health and Advanced Research ijsr-11-7-42633 Original Research Paper Study of Sociodemographic and clinical profile of smoker and non-smoker COPD patients attending a tertiary care centre in North India (Dr) Gajendra Vikram Singh Dr. Dr Sachin Kumar Gupta Dr. Dr Vipin Kumar Dr. July 2022 11 7 01 02